Commutator short-circuit device



A ril 16, 1929. R. w. swm 1,109,415

COMMUTATOR SHORT CIRCUIT DEVICE Filed Feb. 4, 1925 IN ENTO I C "Wu/ AfTORAiEYS.

Patented Apr. 16, 19253,

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FFlfCE.

ROBERT W. SWIFT, 0F WARREN, OHIO.

COMMUTATGR SHORT-CIRCUIT DEVICE.

Application filed February Short circuiting devices using centrifugal force in closing the device with a pre-determined speed of the motor have been in common use. The present invention is designed to simplify such devices so they may be readily manufactured and at the same time so form them that they may be more efrlcient and durable. Features and details of the invention will appear from the specification and claims,

The invention is illustrated in the accompanying drawings as follows Fig. 1 shows an end view of the device, a part being broken away to better show construction.

Fig.2 a side elevation, partly in section, of the device.

1 marks the armature, l the armature shaft, 2 a commutator disc, and 3 commutator bars mounted in the disc, the commutator bars having the over-hanging bevelled edge. These commutator bars form a complete ai1- nulus and are insulated in the usual manner of commutators,

' A fulcrum mounting l is fixed on the shaft 1. This mounting is provided with an annular fulcrum groove 5. Short circuiting bars 6 are arranged in a complete annulus, the bars having the projections 'Z'at their outer ends which project into the groove 5. The inner edges of the bars are bevelled at 8 to conform to the bevel of the ends of the commutator bars so that when the bars 6 swing outwardly under the influence of centrifugal force the bevelled edge 8 will enga e slnoothlv h the bars 3, The bars 6 are preferably slightly narrower than the coinuiutator bars so that at least two of the bars 6 are in contact with each commutator bar thus assuring a short circuit at all of the commutator.

The short circuiting' bars have openings 9 extending through them, these openings when grouped in place forming an annular opening in which is arranged a centripetally acting coil spring 10. A slot 1]. extends through the front edges of the bars 6 thus permitting the spring arranged in annular form to be put in place in the opening 9. A stop ring 12 is mounted on thehub 13 of the plate 4 and positions 4, 1925. Serial No. 6,759.

engages a projection 14 below the opening 11 so as to preventthe disengagement of the fulcrum projections 7 of the bar from the groove 5. The outer periphery of the ring 12 also forms a stop limiting the inward movement of the bars 6, although ordinarily the thickness of the bars is such that they are brought together approximately at tie same time that they reach the periphery of the ring. Thus there is afforded the double stop limiting the inward movement.

The upper end of the fulcrum mounting 4: is provided with a flange 15 which forms a guard over the bars 6. In the operation of the device the bars 6 are held in the inwarc position out of Contact with the commutator bars through the action of the spring 10. As the motor is started and gains speed the centrifugal effort of the bars 6 finally overcomes the spring 10 and the bars swinging outward ly under the influence of centrifugal force engage the commutator bars, thus short circuiting the bars 6 in the usual manner.

lVhat I claim as new is 1. In a commutator short circuit device the combination with a commutator of an annulus of centrifugally actuated bars adapted to move radially into and out of contact with the commutator, said bars having springreceiving openings forming with the assembled bars an annular opening plate at the oppositesice of the bars from the commutator; a tongue and groove connection between the bars and said plate forming a pivot on which the bars swing; and a centripetally acting annular spring arranged in the opening and holding the bars out ofcontact with the comn'iuiator at the lower speeds of the device. the walls of the bars extending over and housing the outer periphery of the spring at every position of the bars. 7

2. In a commutator short circuit device the combination with a commutator of an annulus of centrifugally actuated bars adapted to move radially into and out of contact with the commutator, said bars having spring-receiving openings forming with the assembled bars an annular opening; a fut crum plate at the opposite side of the bars a fulcrum from the commutator; a tongue and groove connection between the bars and said plate forming a pivot on which the bars swing; and a eenti'ipei'ally acting annularly arranged coil spring arranged in ;he opening and holding the bars out of Contact with the commutator at the lower speeds of the device,

the Walls of the bars extenifiing ove and housing the outer periphery of the spring at every position of (he burs.

In testimony whereof I have hereunto set my hand.

W. SWIFT. 

